1. Field of the Invention
This invention relates to a method of forming a crescentic bearing joint in a bone section and to a saw and blade adapted to perform that method.
2. Prior Art
In order to realign distal ends of bone structures it has previously been proposed that an arcuate or crescent shaped cut be made through an intermediate section of the bone to effectively form a crescentic bearing joint section, and that the two ends be rotated about the joint to the desired angle and set in this new relationship.
These arcuate osteotomies were first performed by creating multiple displaced parallel drill holes which were then joined or connected using a small osteotome. It was then proposed to form the arcuate cut through the use of a bone scoop as an attachment for a rotary oscillating saw. See Hallux Valgus Technique Using Crescentic Osteotomies by Dr. Fritz A. Moeller collected in The Evaluation and Treatment of Basic Foot Deformities, Intercontinental Medical Book Corp., New York, 1974. These scoops have thin edges backed by a driving section of increased thickness and the joints formed by these scoops would tend to be non-uniform in depth, creating difficulties when the bone sections were realigned.
Osteotomes have also been developed which employ thin, arcuate blades of uniform cross-section. These blades have a serrated edge and have a driving end adapted to be supported in an oscillating saw. The blades typically have an arcuate extension of approximately 20.degree. and 30.degree. and the entire length of the blade has this same arcuate extension. This design creates several problems when used to perform an arcuate osteotomy. First, it is difficult to form a cut having a substantially larger arcuate extent than the arcuate extent of the blade end without forming an excessively thick cut wherein a substantial volume of bone is destroyed. Accordingly, using these blades of 20.degree. to 30.degree. in arcuate extent, it is not good practice to make cuts of more than about 40.degree. to 45.degree. in extent. As a result the relatively shallow joints thus formed were susceptible to substantial misalignment. Also, the blades had a tendency to flex out of shape if they were formed in lengths required to make cuts of substantial depth.